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This paper proposes a leader–follower control method for multiple snake robot formation. Based on the simplified snake robot model, this work improves the traditional Serpenoid gait mode to a time-varying frequency form. Combined with the line-of-sight (LOS) method, a snake robot trajectory tracking controller is designed to enable the leader to track the desired trajectory at the ideal velocity. Then, the leader–follower following error system of a snake robot formation is established. In this framework, the follower can maintain a preset geometric position relationship with the leader to ensure the fast convergence of the formation location. Lyapunov's theory proves the stability of a snake robot formation error. Simulation and experimental results show that this strategy has the advantages of faster convergence speed and higher tracking accuracy than other current methods. • Based on a simplified snake robot model, a time-varying Serpenoid gait curve is proposed to control speed in real-time and solve traditional gait inefficiency. • This work presents the design of a snake robot trajectory tracker using LOS guidance and a time-varying Serpenoid gait, enabling the body can track the reference trajectory in accordance with the desired time-varying velocity. • A snake robot formation controller is designed based on the leader-follower idea so that the geometric position relationship between the robot follower and the leader can be maintained and converged to the formation position. [ABSTRACT FROM AUTHOR]

Due to the nonlocality and nonlinearity, it is usually difficult to approximate and analyze the semi-linear parabolic differential equations with nonlocal initial conditions. Several researchers have presented different numerical schemes for solving the problems. Only second-order convergence results in spatial direction are proved so far. In order to effectively solve the problem, the problem is approximated by using the fourth-order compact difference method in the spatial direction and the second-order Crank-Nicolson (CN) method in the temporal direction. The fully discrete numerical scheme gives a large system of nonlinear algebraic equations. The fixed-point iteration method with preconditioned GMRES is proposed for solving the resulting nonlinear systems. And the eigenvalues of the coefficient matrix are explored by the Hamilton-Cayley theorem and the investigation of the matrix structure. Stability and convergence of the fully discrete scheme are obtained. Numerical experiments are given to confirm the theoretical results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Formation of KFeO 2 is confirmed via XRD and thermodynamic calculation. • The reactivity of the ilmenite is enhanced with WSA addition. • The reactivity of ilmenite peaks at 10 % WAS addition. • Ilmenite with 10 %WSA addition exhibits highly developed pore structure. • Ilmenite with 10 %WSA addition exhibits the highest oxygen release capability. Chemical looping combustion (CLC) offers a promising approach for biomass utilization. The utilization of biomass as the primary fuel in CLC (bio-CLC) is a way to generate negative CO 2 emissions and thus interesting for climate change mitigation. However, the presence of ash in biomass raises concerns about the performance variation of the oxygen carrier during CLC. This study investigated the impact of adding wheat straw ash (WSA) to the ilmenite oxygen carrier throughout the CLC process. The effects of WSA addition ratio (0–15 %) and cycle number on the performance of oxygen carrier were evaluated. The results showed a progressive enhancement followed by a subsequent reduction in the performance of ilmenite with the increase of WSA addition ratio, and the peak reactivity of ilmenite was attained with 10 % WSA addition. Addition of 15 % WSA resulted in severe particle sintering, causing a slight diminishment in ilmenite reactivity. Furthermore, the mechanisms of the performance variation of ilmenite with WSA addition were explored. The superior redox reactivity and oxygen release capability of the ilmenite with 10 % WSA addition were evidenced by X-ray photoelectron spectroscopy and hydrogen temperature-programmed reduction analysis, respectively. Notably, X-ray diffraction and thermodynamic calculation confirmed the formation of KFeO 2 , which significantly enhanced the reactivity of ilmenite. The specific surface area of the ilmenite was greatly enlarged with 10 % WSA addition, and a porous structure was evidenced by scanning electron microscope. The findings suggest the interaction between the WAS and ilmenite enhances the reactivity of the ilmenite with an optimal WAS addition ratio of 10 %, providing a guidance for the long-term operation of CLC. [ABSTRACT FROM AUTHOR]

[Display omitted] • MSW generation in Yunnan Province is predicted via STIRPAT. • The CO 2 emissions are calculated via IPCC models under various classification scenarios. • Both CTDF and TPDF methods reduce the carbon emissions effectively. • MSW sorting with recycle rate up to 50% is crucial to achieve carbon neutrality. Carbon emissions from municipal solid waste (MSW) are one of the major sources of greenhouse gases. As the world's largest emitter of carbon, China faces a critical challenge in reducing its carbon footprint. This study first employed the STIRPAT model to forecast the production of MSW in Yunnan Province, then followed the Intergovernmental Panel on Climate Change (IPCC) recommended methodologies to calculate and predict the carbon emissions from MSW under four scenarios based on different waste classification methods. The research found that per capita Gross Domestic Product (GDP) and urbanization rate positively influence the generation of MSW, while the proportion of the secondary industry had the opposite effect. Front-end sorting in MSW management is crucial, as enhancing the recycling rate of MSW was a determinative factor in reducing carbon emissions from MSW management. Scenario 1, based on the current situation, resulted in carbon emissions of 3.62 MtCO 2 -eq; whereas, adopting new classification methods in Scenario 4, carbon emissions were reduced to −1.42 MtCO 2 -eq. In Scenario 1, landfilling remained the primary source of carbon emissions in waste treatment, accounting for 70.69%. Achieving carbon neutrality in the MSW treatment process is possible when the recycling rate approaches 50%, and the landfill proportion does not exceed 6%. The study indicates that Scenario 4 offers the best carbon reduction outcome, and the results reveal that promoting waste classification to improve recycling rates is the most effective carbon reduction strategy in MSW management. This study proposed a practical MSW classification pathway to achieve negative carbon emission, which provides valuable guidance for the MSW management. [ABSTRACT FROM AUTHOR]